Micro-optic film materials projecting synthetic images generally comprise: an arrangement of micro-sized image icons; an arrangement of focusing elements (e.g., microlenses, microreflectors); and optionally, a light-transmitting polymeric substrate. The image icon and focusing element arrangements are configured such that when the arrangement of image icons is viewed using the arrangement of focusing elements, one or more synthetic images are projected. These projected images may show a number of different optical effects.
Such film materials may be used as security devices for authentication of banknotes, secure documents and products. For banknotes and secure documents, these materials are typically used in the form of a strip, patch, or thread and can be either partially or completely embedded within the banknote or document, or applied to a surface thereof. For passports or other identification (ID) documents, these materials could be used as a full laminate or inlayed in a surface thereof. For product packaging, these materials are typically used in the form of a label, seal, or tape and are applied to a surface thereof.
One example of a micro-optic security device is known from U.S. Pat. No. 7,738,175, which reveals a micro-optic system that embodies (a) an in-plane image having a boundary and an image area within the boundary that is carried on and visually lies in the plane of a substrate, (b) a control pattern of icons contained within the boundary of the in-plane image, and (c) an array of icon focusing elements. The icon focusing element array is positioned to form at least one synthetically magnified image of the control pattern of icons, the synthetically magnified image providing a limited field of view for viewing the in-plane image operating to modulate the appearance of the in-plane image. In other words, the appearance of the in-plane image visually appears and disappears, or turns on and off, depending upon the viewing angle of the system.
Several drawbacks in this micro-optic system become evident when used in a sealed lens format (i.e., a system utilizing an embedded lens array). First, when the synthetic image is in its “off” state a slight ghost image of the synthetic image may remain visible because of light scattered through or around the focusing optics. These ghost images are especially pronounced in the sealed lens format. Second, the sealed lens format has a relatively high f-number, typically around 2. As will be readily appreciated by one skilled in the field of micro-optics, a higher f-number leads to more rapid movement of synthetic images, but also increases blurriness and the system's sensitivity to manufacturing variations. These drawbacks effectively render this system unsuitable for use in a sealed lens format.
The present invention addresses these drawbacks by providing an optical security device, which comprises:
an optionally embedded array of icon focusing elements;
at least one grayscale in-plane image that visually lies substantially in a plane of a substrate on which the in-plane image is carried; and
a plurality of coextensive (intermingled) control patterns of icons contained on or within the at least one in-plane image forming an icon layer, each control pattern being mapped to areas of the in-plane image having a range of grayscale levels, wherein placement of the control patterns of icons within the in-plane image is determined using one or more control pattern probability distributions associated with each grayscale level within all or part of the in-plane image,
wherein the array of icon focusing elements is positioned to form at least one synthetically magnified image of at least a portion of the icons in each coextensive control pattern of icons, the at least one synthetically magnified image (which intersects with the at least one in-plane image) having one or more dynamic effects, wherein the one or more dynamic effects of the at least one synthetically magnified image are controlled and choreographed by the control patterns of icons.
As the optical security device is tilted the synthetically magnified images demonstrate dynamic optical effects in the form of, for example, dynamic bands of rolling color running through the in-plane image, growing concentric circles, rotating highlights, strobe-like effects, pulsing text, pulsing images, rolling parallel or non-parallel lines, rolling lines that move in opposite directions but at the same rate, rolling lines that move in opposition directions but at different or spatially varying rates, bars of color that spin around a central point like a fan, bars of color that radiate inward or outward from a fixed profile, embossed surfaces, engraved surfaces, as well as animation types of effects such as animated figures, moving text, moving symbols, animated abstract designs that are mathematical or organic in nature, etc. Dynamic optical effects also include those optical effects described in U.S. Pat. No. 7,333,268 to Steenblik et al., U.S. Pat. No. 7,468,842 to Steenblik et al., and U.S. Pat. No. 7,738,175 to Steenblik et al., all of which, as noted above, are fully incorporated by reference as if fully set forth herein.
In an exemplary embodiment, one or more layers of metallization cover an outer surface of the icon layer.
By way of the inventive optical security device, the synthetically magnified image(s) of the in-plane image(s) is always ‘on’. In one exemplary embodiment, as the device is tilted synthetically magnified images in the form of bands of color sweep over the surface of the in-plane image, revealing tremendous detail (i.e., improved visual impact). The bands of color are ‘choreographed’ using the multiple control patterns of icons. The ‘ghost image’, which is troublesome for the micro-optic system of U.S. Pat. No. 7,738,175, helps the optical effects of the present invention to be more convincing by providing a silhouette of the in-plane image at every tilt angle that can always be seen. Also, because the image never turns ‘off’, and is visually defined by the choreographed optical effects (e.g., bands of rolling color), the in-plane image may be made much larger thereby providing enhanced design capability. In addition, the inventive device is less sensitive to manufacturing variations. While any such manufacturing variation may serve to change the angle and shape of the synthetic images, the relative choreography will remain the same, and thus the effect will not be disturbed to the same extent as the prior art system.
The present invention also provides a method for making the optical security device described above, the method comprising:                (a) providing at least one grayscale in-plane image that visually lies substantially in a plane of a substrate on which the in-plane image is carried;        (b) providing a plurality of coextensive (intermingled) control patterns of icons contained on or within the at least one in-plane image forming an icon layer, each control pattern being mapped to areas of the in-plane image having a range of grayscale levels, wherein placement of the control patterns of icons within the in-plane image is determined using one or more control pattern probability distributions associated with each grayscale level within all or part of the in-plane image;        (c) providing an optionally embedded array of icon focusing elements; and        (d) positioning the optionally embedded array of icon focusing elements relative to the icon layer so as to form at least one synthetically magnified image of at least a portion of the icons in each coextensive control pattern of icons, the at least one synthetically magnified image (which intersects with the at least one in-plane image) having one or more dynamic effects, wherein the one or more dynamic effects of the at least one synthetically magnified image are controlled and choreographed by the control patterns of icons.        
In an exemplary embodiment of the inventive optical security device, the device includes a grayscale in-plane image, a plurality of control patterns of icons contained within the in-plane image thereby forming an icon layer, and an array of icon focusing elements positioned to form at least one synthetically magnified image of the control patterns of icons. The method for forming the icon layer in this exemplary embodiment comprises: selecting a grayscale in-plane image; and using the grayscale in-plane image to drive placement of the control patterns of icons within the in-plane image to form the icon layer.
In an exemplary embodiment, the inventive method comprises:                (a) selecting a grayscale in-plane image and scaling the grayscale image to a size suitable for use in the icon layer (e.g., several square millimeters to several square centimeters);        (b) superimposing a tiling onto the scaled grayscale in-plane image, the tiling comprising cells that will contain the control patterns of icons, wherein each cell has a preferred size similar to one or several focusing elements (e.g., several microns to tens of microns);        (c) selecting a numerical range to represent the colors black and white and the various levels of gray in between black and white (e.g., 0 for black, 1 for white, and the continuum of real numbers in between as representing the various levels of gray);        (d) determining the level of grayscale of the scaled grayscale in-plane image in each cell of the superimposed tiling;        (e) assigning to each cell a number which represents the determined level of grayscale and which falls within the selected numerical range (e.g., 0-1), wherein the assigned number is the cell's grayscale value;        (f) selecting a number of control patterns of icons for use in a control pattern palette, and for each control pattern of icons, assigning a range of grayscale levels which fall within the selected numerical range;        (g) specifying a control pattern probability distribution within the in-plane image and for each possible grayscale value, using the control pattern probability distribution to assign a range of random numbers to each control pattern;        (h) providing each cell in the tiling with a random number that falls with the selected numerical range (e.g., 0-1) using a Random Number Generator (RNG);        (i) determining which control pattern will be used to fill each cell using the cell's grayscale value and the cell's random number in conjunction with a mathematical construct which corresponds to the control pattern probability distribution; and        (j) filling each cell with its determined control pattern of icons.        
In another exemplary embodiment of the inventive optical security device, the device includes a sequence of grayscale in-plane images, a set of control patterns of icons for each in-plane image, wherein each set of control patterns of icons is contained within its respective in-plane image, which together form an icon layer, and an array of icon focusing elements positioned to form an animation of the synthetically magnified images of the control patterns of icons. The method for forming the icon layer in this exemplary embodiment comprises: selecting a sequence of grayscale in-plane images, selecting a set of control patterns of icons for each grayscale in-plane image; and using the grayscale in-plane images to drive placement of its respective control patterns of icons within the in-plane image to together form the icon layer.
In an exemplary embodiment, the inventive method comprises:                (a) selecting a sequence of grayscale in-plane images that form an animation and scaling the grayscale images to a size suitable for use in the icon layer (e.g., several square millimeters to several square centimeters);        (b) superimposing a tiling onto each scaled grayscale in-plane image, the tiling comprising cells that will contain the control patterns of icons, wherein each cell has a preferred size similar to one or several focusing elements (e.g., several microns to tens of microns);        (c) selecting a numerical range to represent the colors black and white and the various levels of gray in between black and white (e.g., 0 for black, 1 for white, and the continuum of real numbers in between as representing the various levels of gray);        (d) determining the level of grayscale of the scaled grayscale in-plane image in each cell of the superimposed tiling;        (e) assigning to each cell a number which represents the determined level of grayscale and which falls within the selected numerical range (e.g., 0-1), wherein the assigned number is the cell's grayscale value;        (f) for each grayscale in-plane image that forms the animation, selecting a number of control patterns of icons for use in a control pattern palette, and for each control pattern of icons, assigning a range of grayscale levels which fall within the selected numerical range, wherein the selected number of control patterns of icons constitutes a set of control patterns for the grayscale in-plane image, with each grayscale in-plane image having one set of control patterns of icons;        (g) specifying, for each set of control patterns of icons, a control pattern probability distribution within the respective in-plane image and for each possible grayscale value, using the control pattern probability distribution to assign a range of random numbers to each control pattern;        (h) providing each cell in the tiling with a random number that falls with the selected numerical range (e.g., 0-1) using an RNG;        (i) determining, for each set of control patterns, each set being assigned to a specific and different grayscale image, which control pattern will be used to fill each cell using the cell's grayscale value and the cell's random number in conjunction with a mathematical construct which corresponds to the control pattern probability distribution; and        (j) filling each cell with its determined control pattern of icons, each cell receiving a determined control pattern from each set of control patterns of icons.        
The present invention further provides a method for increasing design space, reducing sensitivity to manufacturing variations, and reducing blurriness of images formed by an optical security device, the optical security device including at least one in-plane image, a plurality of control patterns of icons contained within the in-plane image forming an icon layer, and an array of icon focusing elements positioned to form at least one synthetically magnified image of the control patterns of icons, the method comprising: using at least one grayscale in-plane image; and using coordinated control patterns of icons on or within the in-plane image to control and choreograph one or more dynamic effects of the synthetically magnified images.
The present invention further provides sheet materials and base platforms that are made from or employ the inventive optical security device, as well as documents made from these materials.
In an exemplary embodiment, the inventive optical security device is a micro-optic film material such as an ultra-thin (e.g., a thickness ranging from about 1 to about 10 microns), sealed lens structure for use in banknotes.
In another exemplary embodiment, the inventive optical security device is a sealed lens polycarbonate inlay for base platforms used in the manufacture of plastic passports.
Other features and advantages of the invention will be apparent to one of ordinary skill from the following detailed description and accompanying drawings.
Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. All publications, patent applications, patents and other references mentioned herein are incorporated by reference in their entirety. In case of conflict, the present specification, including definitions, will control. In addition, the materials, methods/processes, and examples are illustrative only and not intended to be limiting.